Fiber optic local convergence points for multiple dwelling units

ABSTRACT

There are provided fiber optic local convergence points (“LCPs”) adapted for use with multiple dwelling units (“MDUs”) that facilitate relatively easy installation and/or optical connectivity to a relatively large number of subscribers. The LCP includes a housing mounted to a surface, such as a wall, and a cable assembly with a connector end to be optically connected to a distribution cable and a splitter end to be located within the housing. The splitter end includes at least one splitter and a plurality of subscriber receptacles to which subscriber cables may be optically connected. The splitter end of the cable assembly of the LCP may also include a splice tray assembly and/or a fiber optic routing guide. Furthermore, a fiber distribution terminal (“FDT”) may be provided along the subscriber cable to facilitate installation of the fiber optic network within the MDU.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to fiber optic local convergence pointsand associated fiber optic hardware, and more particularly, to fiberoptic local convergence points adapted for multiple dwelling units.

2. Description of Related Art

To provide improved performance to subscribers, fiber optic networks areincreasingly providing optical fiber connectivity directly to thesubscribers. As part of various fiber-to-the-premises (FTTP),fiber-to-the-home (FTTH), and other initiatives (generally described asFTTX), such fiber optic networks are providing the optical signals fromdistribution cables through local convergence points (“LCPs”) to fiberoptic cables, such as drop cables, that are run directly to thesubscribers' premises. Such optical connectivity is increasingly beingprovided to multiple dwelling units (“MDUs”) in part because of therelatively large density of subscribers located in an MDU.

MDUs include apartments, condominiums, townhouses, dormitories,hotels/motels, office buildings, factories, and any other collection ofsubscriber locations that are in relatively close proximity to oneanother. MDUs typically are all provided in a single indoor environment,such as an office or condominium; however, MDUs may also include aplurality of individual structures, such as apartment complexes.Typically, if an MDU comprises multiple structures, the optical fibersextending between the structures are adapted for outdoor environments,whereas the optical fibers extending within the structures are adaptedfor indoor environments. Most conventional MDUs include an LCP locatedin a generally central and selectively accessible location, such as thebasement, utility closet, or the like, or the LCP may be located outsidethe MDU on an exterior wall, in a pedestal, in a handhole, or the like.The LCP includes at least one fiber optic cable that optically connectsto a distribution cable. The LCP also includes a connection point wherethe subscriber cables routed through the building are opticallyconnected to the distribution cable.

Conventional LCPs for such MDUs are generally sized according to thenumber of subscribers to be serviced through the LCP, and many of thehigh density MDUs require large, expensive LCPs that may be difficult toinstall and/or transport. In addition, conventional LCPs often requireskilled technicians to install the LCP and route the associatedsubscriber cables. Furthermore, highly skilled technicians are requiredto optically connect, often by splicing, the distribution cable to theLCP and to optically connect and route the subscriber cables to the LCP.Therefore, a need exists for LCPs that are cost-effective, arerelatively small in size, and may be installed and maintained byrelatively unskilled technicians.

BRIEF SUMMARY OF THE INVENTION

The various embodiments of the present invention address the above needsand achieve other advantages by providing LCPs and associated fiberoptic hardware components that provide optical connectivity torelatively large numbers of subscribers using relative small fiber optichardware components. In addition, some embodiments of the presentinvention enable installation of the LCPs and associated components byrelatively unskilled technicians by removing the need to splice any ofthe connections between the distribution cable and the subscriberlocation and by providing optical fibers having significantly smallerminimum bend radii to provide more versatility when routing thesubscriber cables through the building.

In one embodiment of the present invention, a fiber optic localconvergence point (“LCP”) adapted for use with a multiple dwelling unitis provided. The LCP is adapted to optically connect at least oneoptical fiber of a distribution cable to at least one subscriber opticalfiber. The LCP comprises a housing having an interior cavity defined bya plurality of sides and by a cover that is selectively moveable from anopened position to a closed position to thereby provide access to theinterior cavity when the cover is in the opened position. The housingalso includes at least one surface adapted for mounting the LCP to astructure, and the housing further comprises at least one openingthrough the housing for the passage of at least one optical fiber. TheLCP also comprises a cable assembly with a connector end adapted foroptical connection to the at least one optical fiber of the distributioncable and with a splitter end generally opposite the connector end ofthe cable assembly. The splitter end of the cable assembly defines acasing with an exterior surface that defines a plurality of receptaclesadapted to selectively receive fiber optic connectors that are opticallyconnected to the subscriber optical fiber. The connector end of thecable assembly is optically connected to the splitter end with at leastone cable assembly optical fiber. In addition, the splitter endcomprises at least one splitter that optically connects the cableassembly optical fiber with the plurality of receptacles. The splitterend of the cable assembly is adapted to be removably received within thehousing of the LCP, and the splitter end is adapted to be receivedwithin the housing without opening the casing of the splitter end

Further embodiments of the present invention provide a cable assemblyadapted for use in a multiple dwelling unit to optically connect atleast one optical fiber of a distribution cable to at least onesubscriber optical fiber. The cable assembly comprising a connector endadapted for optical connection to the at least one optical fiber of thedistribution cable and with a splitter end generally opposite theconnector end of the cable assembly. The splitter end of the cableassembly defines a casing with an exterior surface that defines aplurality of receptacles adapted to selectively receive fiber opticconnectors that are optically connected to the subscriber optical fiber.The connector end of the cable assembly is optically connected to thesplitter end with at least one cable assembly optical fiber. Inaddition, the splitter end comprises at least one splitter thatoptically connects the cable assembly optical fiber with the pluralityof receptacles. Some embodiments of the present invention include atleast one microstructured optical fiber in the cable assembly. Themicrostructured optical fiber comprises a core region and a claddingregion surrounding the core region, the cladding region comprises anannular hole-containing region comprised of non-periodically disposedholes. The microstructured fiber of some embodiments of the presentinvention has an 8 mm macrobend induced loss at 1550 nm of less than 0.2dB/turn.

Still further embodiments provide related fiber optic hardware adaptedfor use in MDUs and other facilities. For example, the present inventionprovides fiber optic splice tray assemblies defining a density of spliceholders per unit of volume of the splice tray assembly of at least 5single splices/in³ and/or at least 10 mass fusion splices/in³, fiberoptic splitter modules that includes a splitter axis orthogonal to anopening axis and/or that define a density of splits per unit volume ofthe housing of at least 5 splits/in³, fiber optic routing guides adaptedto store an amount of length of optical fiber (900 μm diameter) per unitof volume of a housing of at least 10 in/in³, and fiber distributionterminals (“FDTs”) defining a density of fiber optic output receptaclesper unit of volume of the housing of at least 10 receptacles/in³ for aninput subscriber optical cable and of at least 6 receptacles/in³ for aconnectorized input subscriber optical cable. All of these fiber optichardware components provide a significant improvement to the comparableconventional components, thus allowing them to be more easily handledand allowing them to be installed in a greater number of locations basedupon the network's requirements and/or the technician's preferences.Therefore, the LCPs, cable assemblies, FDTs, and other components ofvarious embodiments of the present invention provide for cost-effective,reduced-size, and easily-installed fiber optic networks for MDUs.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale and are meant to be illustrative and not limiting, and wherein:

FIG. 1A is a perspective view of a local convergence point (“LCP”) inaccordance with one embodiment of the present invention with the coverremoved and the splitter end of the cable assembly opened;

FIG. 1B is a top view the LCP of FIG. 1A illustrating the optical fiberrouting within the splitter end of the cable assembly and illustratingthe subscriber optical fiber;

FIG. 1C is a side view of the bottom of the LCP of FIG. 1A illustratingthe openings for the at least one cable assembly optical fiber (left)and the at least one subscriber optical fiber (right);

FIG. 2A is a perspective view of a LCP in accordance with anotherembodiment of the present invention, illustrating the housing of the LCPremovably receiving the splitter end of the cable assembly by rotatingthe splitter end into the housing;

FIG. 2B is a top view of the LCP of FIG. 2A illustrating the splitterend of the cable assembly at a rotated position;

FIG. 2C is a bottom view of the LCP of FIG. 2A illustrating the splitterend of the cable assembly at a rotated position of about 45 degrees;

FIG. 3A is a perspective view of a LCP in accordance with yet anotherembodiment of the present invention, illustrating the housing asincluding a plurality of splitter modules, a splice tray assembly, fiberoptic routing guides, and a subscriber termination field comprising aplurality of receptacles, wherein the LCP is free of a splitter end of acable assembly;

FIG. 3B is a perspective view of the LCP of FIG. 3A with a coverattached and in the closed position;

FIG. 3C is a top view of the LCP of FIG. 3A illustrating the splittermodules, the splice tray assembly, the fiber optic routing guides, andthe subscriber termination field;

FIG. 4A is a perspective view of a LCP in accordance with a furtherembodiment of the present invention, illustrating the splitter end ofthe cable assembly as including a plurality of splitter modules, asplice tray assembly, fiber optic routing guides, and a subscribertermination field comprising a plurality of receptacles;

FIG. 4B is a top view of the LCP of FIG. 4A illustrating the splittermodules, the splice tray assembly, the fiber optic routing guides, andthe subscriber termination field within the splitter end of the cableassembly;

FIG. 5A is a perspective view of a LCP in accordance with a stillfurther embodiment of the present invention, illustrating a plurality ofsplitter modules housed within the interior cavity of the housing,wherein the splitter modules define multi-fiber output receptacles;

FIG. 5B is a perspective view of the LCP of FIG. 5A illustrating thesplitter modules with the access cover removed to allow selectiveinstallation and/or removal of the individual splitter modules;

FIG. 5C is a top view of the LCP of FIG. 5A with the access coverinstalled;

FIG. 5D is a side view of the bottom of the LCP of FIG. 5A illustratingthe openings providing passage for the optical fibers to and from thedistribution cable and/or the subscriber termination points;

FIG. 6 is a side view of a MDU that includes an LCP and associated fiberoptic hardware in accordance with another embodiment of the presentinvention wherein the fiber optic network does not include at least oneFDT such that the subscriber optical fibers are routed directly to thesubscriber termination points without the use of the FDT and/or thesubscriber drop optical fibers;

FIG. 7 is a side view of a multiple dwelling unit (“MDU”) that includesan LCP and associated fiber optic hardware in accordance with oneembodiment of the present invention, illustrating the optical signalrouting from the distribution cable to LCP via the cable assemblyoptical fiber to the LCP, then to the FDT via the subscriber opticalfiber, and finally to the subscriber termination point via thesubscriber drop optical fiber;

FIG. 8A is a perspective view of a fiber distribution terminal (“FDT”)in accordance with one embodiment of the present invention illustratinga single input optical cable comprising a plurality of input opticalfibers and an output opening comprising a plurality of fiber opticoutput receptacles;

FIG. 8B is a perspective view of the FDT of FIG. 8A further comprising aremovable portion adapted to selectively cover the fiber optic outputreceptacles when at least one connector is received in the fiber opticreceptacles;

FIG. 8C is a top view of the FDT of FIG. 8A illustrating the mountingflanges of the FDT;

FIG. 8D is a side view of the bottom of the FDT of FIG. 8A illustratingthe input opening in a sidewall as comprising a through-hole for passageof at least one input optical fiber;

FIG. 9A is a perspective view of a FDT in accordance with a furtherembodiment of the present invention illustrating an input openingcomprising a fiber optic input receptacle and an output openingcomprising a plurality of fiber optic output receptacles;

FIG. 9B is a top view of the FDT of FIG. 9A illustrating the mountingflanges of the FDT;

FIG. 9C is a side view of the bottom of the FDT of FIG. 9A illustratingthe input opening in a sidewall as comprising a fiber optic inputreceptacle adapted to receive a multi-fiber connector of the subscriberoptical fiber;

FIG. 10A is a perspective view of a FDT in accordance with a stillfurther embodiment of the present invention with a top cover removed,illustrating an input opening comprising a fiber optic input receptacleand an output opening comprising a plurality of fiber optic outputreceptacles, wherein the FDT defines an input opening axis that isgenerally orthogonal to an output opening axis;

FIG. 10B is a top view of the FDT of FIG. 10A illustrating the internalrouting of the optical fibers from the input opening to the outputopening;

FIG. 10C is a side view of the output opening of the FDT of FIG. 10Aillustrating the plurality of fiber optic output receptacles adapted toreceive MU connectors of the subscriber drop optical fibers;

FIG. 11A is a perspective view of a FDT in accordance with yet anotherembodiment of the present invention with a top cover removed,illustrating an input opening comprising a fiber optic input receptacleand an output opening comprising a plurality of fiber optic outputreceptacles, wherein the FDT defines an input opening axis that isgenerally parallel to an output opening axis;

FIG. 11B is a top view of the FDT of FIG. 11A illustrating the internalrouting of the optical fibers from the input opening to the outputopening;

FIG. 11C is a side view of the output opening of the FDT of FIG. 11Aillustrating the plurality of fiber optic output receptacles adapted toreceive MU connectors of the subscriber drop optical fibers;

FIG. 12A is a perspective view of a fiber optic splice tray assembly inaccordance with one embodiment of the present invention illustratedabove a prior art splice tray assembly, wherein the splice tray assemblyof the present invention defines a significantly greater density ofsplice holders per unit volume of the splice tray assembly as comparedto the prior art splice tray assembly;

FIGS. 12B and 12C are top and side views, respectively, of the splicetray assembly of the embodiment of the present invention of FIG. 12Aillustrated to scale relative to the prior art splice tray assembly ofFIGS. 12D and 12E;

FIGS. 12D and 12E are top and side views, respectively, of the prior artsplice tray assembly of FIG. 12A illustrated to scale relative to thesplice tray assembly of FIGS. 12B and 12C;

FIG. 13A is a perspective view of a fiber optic splitter module inaccordance with one embodiment of the present invention illustratedabove a prior art splitter module, wherein the splitter module of thepresent invention defines a significantly greater density of outputoptical fibers per unit volume of the housing as compared to the priorart splice tray assembly, and wherein the splitter module of the presentinvention defines a splitter axis that is generally orthogonal to anopening axis;

FIGS. 13B and 13C are top and side views, respectively, of the splittermodule of the embodiment of the present invention of FIG. 13Aillustrated to scale relative to the prior art splitter module of FIG.13A;

FIGS. 13D and 13E are top and side views, respectively, of the prior artsplitter module of FIG. 13A illustrated to scale relative to thesplitter module of FIGS. 13B and 13C;

FIG. 14A is a perspective view of a fiber optic routing guide inaccordance with one embodiment of the present invention illustratedabove a prior art routing guide, wherein the routing guide of thepresent invention is adapted to store a significantly greater amount oflength of optical fiber per unit volume of the housing as compared tothe prior art routing guide;

FIGS. 14B and 14C are top and side views, respectively, of the routingguide of the embodiment of the present invention of FIG. 14A illustratedto scale relative to the prior art routing guide of FIG. 14A; and

FIGS. 14D and 14E are top and side views, respectively, of the prior artrouting guide of FIG. 14A illustrated to scale relative to the routingguide of FIGS. 14B and 14C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, the invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Although apparatus and methods for providing localconvergence points (“LCPs”) for multiple dwelling units (“MDUs”) aredescribed and shown in the accompanying drawings with regard to specifictypes of LCPs and associated fiber optic hardware, it is envisioned thatthe functionality of the various apparatus and methods may be applied toany now known or hereafter devised LCPs and associated fiber optichardware in which it is desired to provide optical connectivity forMDUs. Like numbers refer to like elements throughout.

With reference to FIG. 1A-14E, various LCPs and associated fiber optichardware in accordance with various embodiments of the present inventionare illustrated. It should be appreciated that the many embodiments ofthe present invention include various combinations of the fiber optichardware described herein. Furthermore, certain embodiments to notinclude all of the components described herein, non-limiting examples ofcomponents that are not included in all embodiments include fiber opticsplice tray assemblies, fiber optic routing guides, fiber distributionterminals, subscriber drop optical fibers, and others. In addition,although many embodiments referred to herein are described as havingcertain dimensions and densities, it should be appreciated that thedimensions are merely exemplary and limiting.

Turning now to the LCP 10 of FIGS. 1A-1C, the LCP is adapted for usewith a MDU to optically connect at least one optical fiber of adistribution cable to at least one subscriber optical fiber. The LCPsdescribed herein are intended for indoor use; however, furtherembodiments are adapted for indoor and/or outdoor use and may be mountedto any surface. The LCP 10 of FIGS. 1A-1C include a housing 12comprising an interior cavity 14 defined by a plurality of sides 16 andby a cover (not shown) that is selectively moveable from an openedposition to a closed position to thereby provide access to the interiorcavity when the cover is in the opened position. The interior cavity 14of the LCP 10 is not hermetically sealed and may include a variety ofopenings to provide access to the interior cavity. The housing 12 ofFIGS. 1A-1C comprises at least one surface 16 adapted for mounting theLCP 10 to a structure (not shown) such as wall in a building to provideone non-limiting example. The housing 12 of FIGS. 1A-1C is similar tostandard plastic network interface device (“NID”) housings offered byCorning Cable Systems of Hickory, N.C.; however, the housings of furtherembodiments of the present inventions include housings of any shapeand/or material sufficient to provide the necessary opticalconnectivity, environmental protection, and/or structural propertiesrequired for the particular application. The housing 12 furthercomprises at least one opening 18 and 20 through the housing for thepassage of at least one optical fiber such as an optical fiber 22optically connected to at least one optical fiber of a distributioncable (not shown) and such as a subscriber optical fiber 24 opticallyconnected to a subscriber termination point (not shown). It should beappreciated that the opening 20 provides passage for a plurality ofsubscriber optical fibers which are shown generally outside the housing12, but for illustrative purposes only one subscriber optical fiber 24is shown inside the housing 12.

The LCP 10 of FIGS. 1A-1C also includes a cable assembly 30 comprising aconnector end (not shown) adapted for optical connection to at least oneoptical fiber of a distribution cable (not shown) of the fiber opticnetwork. The connector end includes a preconnectorized (factory-preparedconnector) end that may be conveniently connected to a connector at anaccess point on the distribution cable. Conversely, the connector end offurther embodiments may not include any connector such that the opticalfiber(s) of the connector end must be spliced to the optical fiber(s) ofthe distribution cable at an access point (that may or may not befactory-prepared) on the distribution cable. Returning again to theembodiment of FIGS. 1A-1C, generally opposite the connector end of thecable assembly 30 is provided a splitter end 32 that defines a casing 34with an exterior surface 36 that defines a plurality of receptacles 38adapted to selectively receive fiber optic connectors 40 that areoptically connected to the at least one subscriber optical fiber 24. Atleast one cable assembly optical fiber 22 extends from the connector endto the splitter end to optically connect the splitter end to theconnector end (and the distribution cable when the LCP is installed).

The cable assembly optical fiber 22 of FIGS. 1A-1C is opticallyconnected to a splitter 42, such as a 1×8, 1×16, 1×32, and/or 1×64splitters to provide non-limiting examples of splitters, that splits theoptical signal from the optical fiber 22 to a plurality of pigtails 44.The pigtails 44 are optical fibers optically connected to the splitterand that terminate in a connector (not shown) adapted to be received inthe receptacles opposite the exterior surface 36, such that receipt ofthe fiber optic connector 40 by the receptacle 38 optically connects thepigtail to the subscriber optical fiber. Further embodiments of thepresent invention provide alternative devices to optically connect thecable assembly optical fiber to the plurality of receptacles. Thesplitter end 32 of FIGS. 1A-1C includes nine 1×32 splitters 42 thusproviding up to 288 receptacles 38 adapted to selectively receive fiberoptic connectors 40 that are optically connected to the at least onesubscriber optical fiber 24. Thus the cable assembly 30 includes ninecable assembly optical fibers to optically connect each of the splitters42 to the distribution cable. However, further embodiments of thepresent invention include any number of cable assembly optical fibers,splitters, and receptacles, which are typically dictated by the numberof subscriber termination points to be provided within the MDU (and thenumber of LCPs to be provided in the MDU, as some MDUs include multipleLCPs).

The splitter end 32 of the cable assembly 30 of the LCP 10 of FIG. 1A-1Cis adapted to be removably received within the housing 12 of the LCP.Furthermore, the splitter end 32 of FIGS. 1A-1C is adapted to bereceived within the housing without opening the casing 34 of thesplitter end. Therefore, the LCP 10 may be conveniently installed by afield technician by simply mounting the housing 12 to an appropriatesurface, optically connecting the connector end of the cables assembly30 to the distribution cable, and then inserting the splitter end 32into the housing. Further embodiments of the present invention comprisean LCP that does not include a housing, but simply comprises the cableassembly, such as the cable assembly 30 of FIGS. 1A-1C. Such us of acable assembly without the housing would be suitable for certainapplications where environmental protection, security, and otherconsiderations are less of a concern. For certain embodiments of the LCPwithout a housing, the casing of the cable assembly includes features toassist in the convenient mounting of the splitter end (and in someembodiments, the connector end) of the cable assembly relative to theMDU.

Turning again to the LCP 10 of the illustrated embodiments, receipt ofthe splitter end 32 into the housing 12 is illustrated in FIGS. 2A-2C.An interior surface of the housing 12 includes a clip 46 into which aprotrusion of the casing 34 may be selectively received to create ahinge to allow the splitter end to be rotatably joined to the housing ofthe LCP 10. To install the splitter end 32 into the housing 12, thetechnician simply connects the protrusions to the respective clips 46and then rotates the splitter end inward. The splitter end 32 isillustrated in FIGS. 2A-2C as being at about a 45 degree angle relativeto the housing; however, the splitter end may rotate any amountpermitted by the housing (for this example from at least 0 degrees to 90degrees); however, further embodiments of the present invention includesplitter ends that rotate at any angles relative to the housing andsplitter ends that are selectively received by the housing inalternative fashions, such as with fasteners, with retaining clipsrequiring linear insertion or alternative insertion techniques, withadhesives, and with any suitable retention devices and/or techniques. Aspreviously mentioned, the splitter end 32 of FIGS. 1A-2C is adapted tobe received within the housing without opening the casing 34 of thesplitter end. Furthermore, the splitter end of the cable assembly isadapted to be removably received within the housing 12 of the LCP 10without requiring any splice operation and/or connectorizationoperation. The splitter end 32 is factory prepared to include all thenecessary optical connectivity from the connector end to the pluralityof receptacles such that a technician would not be required to open thecasing 34. However, it should be appreciated that the casings of someembodiments of the present invention provide devices and/or techniquesfor selectively opening and closing the casing 34 in the field to permitselective access within the casing. Still further embodiments of thepresent invention include splitter ends that do not include any casing,such as the LCP 50 of FIGS. 3A-3B.

The LCP 50 of FIGS. 3A-3C is one embodiment of the present inventionthat does not include a casing for the splitter end 52. Rather thanhaving an encased splitter end, the splitter end 52 of FIGS. 3A-3C ispositioned within the interior cavity 54 as individual components,preferably in the factory, but possibly in the field. FIG. 3Billustrates the cover 56 that is selectively movable from an openedposition to a closed position (FIG. 3B) to provide access to theinterior cavity 54. The splitter end 52 of the LCP 50 may be factoryprepared to include all the fiber optic hardware components shown and toallow a field technician to provide a number of operations on thevarious components. The splitter end 52 includes a plurality ofsplitters 58, at least one splice tray assembly 60, at least one fiberoptic routing guide 62, and a subscriber termination field comprising aplurality of receptacles 64. By providing the fiber optic hardwarecomponents individually within the LCP 50, a network provider is giventhe option of purchasing the LCP with the minimum amount of fiber optichardware components required at the time of installation and then addadditional components as additional subscribers need connection to thenetwork. Still further advantages are provided by providing the splitterend 52 of FIGS. 3A-3C. The cable assembly optical fiber(s) (not shown)is routed to the splitters 58 where the optical signal is split into aplurality of optical fibers. The optical fibers may be spliced, byeither single splices for individual fibers or mass fusion splicing formulti-fiber cables such as ribbon cables, and placed within the splicetray assembly. The optical fibers from the splitters may be spliced topigtails that may be inserted into a side of the receptacles 64 oppositethe side into which the connector of the subscriber optical fiber willbe received. Although the splice tray assembly 60 does accommodate acertain amount of fiber optic slack, such as an amount of slacknecessary to perform the splice operation, the fiber optic routingguides 62 also provide slack storage for the optical fibers from thesplitters and/or for the pigtails. Still further embodiments of thepresent invention may provide additional and/or alternative fiber opticcomponents in the interior cavity of the housing of the LCP.

Turning now to the LCP 70 of FIGS. 4A and 4B, the splitter end 72 doesinclude fiber optic splice tray assembly 74 and fiber optic routingguides 76 within the casing 78. The splitter end 72 also includes aplurality of splitters 80 and the plurality of receptacles 82 similar tothe embodiments of FIGS. 1A-2C. Therefore, the LCP 70 of FIGS. 4A and 4Bincludes some of the functionality of the LCP 50 of FIGS. 3A-3C, whilealso providing the ease of installation of the LCP 10 of FIGS. 1A-2C.Still further advantages can be realized by combining the various fiberoptic hardware components and techniques of the embodiments of FIGS.1A-4B and further embodiments of the present invention.

In addition to providing convenient installation of the LCP withinand/or near the MDU, the LCPs of certain embodiments of the presentinvention also provide improved density of connections, whichsignificantly reduces the cost of the hardware and enables techniciansto more easily install the LCP and associated fiber optic hardware andto increase the possible places the LCP and associated fiber optichardware may be installed and/or mounted. Whereas prior art LCPsgenerally define a width of 13.5 inches, a height of 15.5 inches, and adepth of 5.5 inches along the exterior of the LCP while providing only48 receptacles for subscriber optical fibers, the LCPs of theillustrated embodiments of the present invention generally define awidth of 9.8 inches, a height of 12.6 inches, and a depth of 3.8 incheswhile providing 288 receptacles for subscriber optical fibers.Therefore, the prior art LCPs define a density of receptacles per unitof volume of the housing of about 0.042 receptacles/in³, and the LCPs ofthe illustrated embodiments define a density of receptacles per unit ofvolume of the housing of about 0.614 receptacles/in³, which is asignificant improvement in density that can be used to provide smallerLCPs and/or provide additional optical connectivity with the LCPs of thepresent invention. Various embodiments of the present inventionpreferably provide a density of receptacles per unit of volume of thehousing from about 0.10 receptacles/in³ to about 4.0 receptacles/in³,more preferably a density of receptacles per unit of volume of thehousing from about 0.25 receptacles/in³ to about 2.0 receptacles/in³,and still more preferably a density of receptacles per unit of volume ofthe housing from about 0.50 receptacles/in³ to about 1.0receptacles/in³.

The LCPs of FIGS. 1A-4B include receptacles that are adapted to receiveconnectors of subscriber optical fibers that comprise 5 mm opticalconnectors, which may be arranged in relatively dense patterns as adistance of only 5 mm is required between centers in both lateral andlongitudinal directions (“5 mm optical connectors”). Still furtherembodiments of the present invention include receptacles adapted toreceive MU connectors that may also be arranged in relatively densepatterns, but require 4.5 mm to 5 mm between centers in either a lateralor longitudinal direction and about 10 mm in the opposite direction;thereby requiring slightly large volume than the 5 mm opticalconnectors. Additional embodiments of the present invention includereceptacles adapted to receive SC, LC, ST, FC, MT-RJ, MTP, and otherfiber optic connectors and adapted to receive single-mode or multimodefibers in simplex, duplex, or multi-fiber arrangements.

FIGS. 5A-5D illustrate yet another LCP 90 of the present invention,wherein the LCP includes a plurality of multi-fiber receptacles 92adapted to received multi-fiber connectors (not shown) of the subscriberoptical fibers. The housing 94 of the LCP 90 defines an interior cavity96 into which a plurality of splitter modules 98 may be received. Ratherthan providing a cable assembly as in the embodiments discussed above,the LCP 90 is adapted to house a plurality of splitter modules 98. Thesplitter modules 98 of the illustrated embodiments includes a singleinput opening 100 and a plurality of output openings 102 to whichoptical fibers may be routed and connected via multi-fiber connectors(not shown). The optical fibers pass through the openings 104 and 106similar to the embodiments described above; however, it would bepossible to change the routing if desired by the technician. Thesplitter modules 98 include a splitter (not shown) that splits theoptical signal received through the input opening 100 to the pluralityof receptacles of the output openings. The splitter modules 98 areinstalled by fastening them to brackets 108 provided in the interiorcavity 96 of the housing 94; however, further embodiments may installthe splitter modules in alternative fashions, such as by providing asplitter end of a cable assembly wherein the splitter end is adapted toreceive at least one splitter module within the splitter end, todescribe one non-limiting example. The LCP 90 of FIGS. 5A-5D includes anaccess cover 110 to limit access to the splitter modules to technicians.The splitter modules of certain embodiments of the present inventioninclude the splitter modules of FIGS. 13A-13D described in more detailbelow.

FIGS. 6 and 7 illustrate the LCPs (not to scale) of certain embodimentsof the present invention installed in an MDU 120. The MDU 120 of FIGS. 6and 7 comprises an apartment building having nine dwelling units 122 forillustrative purposes only. The LCP 124 is positioned on the groundfloor or basement in the illustrated embodiment; however, the LCP offurther embodiments is positioned at any location relative to the MDU.The LCP 124 includes a cable assembly 126 that is optically connected toa distribution cable 128 via the cable assembly optical fiber(s) 130 asdescribed above. As also described above, the subscriber optical fibers132 that are connected to the receptacles of the LCP 124 exit the LCPand extend throughout the MDU. The subscriber optical fibers 132 of FIG.6 extend directly to each dwelling unit and terminate at a subscribertermination point 134, such as an adapter in a wall outlet, an adapterin a floor panel, an adapter behind a ceiling tile, or the like suchthat the subscriber can optically connect directly (or indirectly insome situations) to the subscriber optical fiber 132. Although theoptical fibers 130 and 132 include arrows pointing in the direction ofthe subscriber termination points 134, it should be appreciated thatoptical signals may be passed in either direction as required for theparticular application; the arrows are merely provided for illustrativepurposes.

FIG. 7 is also provided to illustrate embodiments in which thesubscriber optical fiber 132 is optically connected to a fiberdistribution terminal (“FDT”) 136 (not to scale) rather than thesubscriber termination point 134. FDTs are provided to simplify therouting and installation of the optical fibers between the LCP 124 andthe subscriber termination points 134 by allowing the subscriber opticalfibers 132 to be grouped between the LCP and FDT and then separated atthe FDT. More specifically, the subscriber optical fibers 132 of FIG. 7comprise multi-fiber cables comprising a plurality of optical fibers,such as ribbon fiber to provide one non-limiting example. As explainedmore fully below, the subscriber optical fiber 132 is separated intomultiple subscriber drop optical fibers 138 that are routed from the FDT136 to the subscriber termination points 134. As shown in FIG. 7, eachfloor of the MDU 120 includes a FDT, such that each of the threesubscriber optical fibers 132 is divided into three subscriber dropoptical fibers 136. Accordingly, there are fewer optical fibers and/orcables extending between the floors of the MDU thus simplifying routingof optical fibers through the MDU. Although floors of an MDU aredescribed in the illustrated embodiments, it should be appreciated thatFDTs may be used to facilitate optical fiber routing to any layout ofareas within an MDU.

Turning now to the FDTs of FIGS. 8A-11C, various FDTs are included inthe present invention. The FDT 140 of FIGS. 8A-8D comprises a generallyrectangular housing 142 that defines a top wall 144, a bottom wall 146,and a sidewall 148 extending therebetween. The FDT 140 includes an inputopening 150 defined in the sidewall 148, and the input opening isadapted to receive at least one input optical fiber. For the FDT 140 ofFIGS. 8A-8D, the input opening 150 receives a single subscriber opticalcable 152 that comprises twelve subscriber optical fibers. The FDT 140defines a direct cable input as compared to the multi-fiber connectorinput of the embodiment of FIGS. 9A-9C described below. The FDT 140 ofFIGS. 8A-8D also includes an output opening 154 defined in the sidewall148. The output opening 154 comprises a plurality of fiber optic outputreceptacles 156 adapted to receive fiber optic connectors, such as froma subscriber drop optical fiber (not shown), to optically connect thefiber optic connector to a respective one of the input optical fibers.The FDTs of further embodiments of the present invention are adapted toreceive any number of input optical fibers and provide any number offiber optic output receptacles. The FDT 140 of FIG. 8B includes aremovable portion 158 adapted to selectively cover the fiber opticoutput receptacles when one or more fiber optic connectors are receivedin the fiber optic output receptacles to generally protect theconnectors from unintentional disconnection, as well as otherundesirable problems that may be created by unintentional contact offoreign objects with the connectors. The removable portion 158 of FIG.8B may be easily connected and disconnected by a technician using clips,fasteners, and the like when the technician accesses the output opening154 and the fiber optic output receptacles 156. The FDT 140 alsoincludes one or more mounting flanges 159 to provide easy installationof the FDT within the MDU.

The FDT 140 of FIGS. 8A-8D provides a significant advantage over priorart FDTs in that the FDT 140 provides easy installation andconnectivity, as well as requiring significantly less volume than priorart FDTs. Prior art FDTs typically use a housing similar to the LCPhousings described above or an even larger cabinet or the like.Therefore, prior art FDTs provide for only about a density ofreceptacles per unit of volume of the housing of about 0.042receptacles/in³. However, the FDT 140 of FIGS. 8A-8D generally defines(not including the mounting flanges or removable portion area) a widthof 1.38 inches, a height of 1.35 inches, and a depth of 0.55 incheswhile providing 12 receptacles for subscriber optical fibers. Therefore,the FDT 140 provides a density of receptacles per unit of volume of thehousing of about 11.7 receptacles/in³, which is a significantimprovement in density over the prior art. Various embodiments of thepresent invention preferably provide direct cable input FDTs having adensity of receptacles per unit of volume of the housing from about 1.0receptacles/in³ to about 40 receptacles/in³, more preferably a densityof receptacles per unit of volume of the housing from about 5.0receptacles/in³ to about 20 receptacles/in³, and still more preferably adensity of receptacles per unit of volume of the housing from about 10receptacles/in³ to 0.3 about 15 receptacles/in³.

Referring now to the FDTs of FIGS. 9A-9C, a multi-fiber connector inputFDT 160 is provided. The FDT 160 of FIGS. 9A-9C comprises a generallyrectangular housing 162 that defines a top wall 164, a bottom wall 166,and a sidewall 168 extending therebetween. The FDT 160 includes an inputopening 170 defined in the sidewall 168, and the input opening isadapted to receive at least one input optical fiber. For the FDT 160 ofFIGS. 9A-9C, the input opening 170 provides a multi-fiber receptacle 172to which a multi-fiber connecter may be selectively received. Themulti-fiber connector of the subscriber optical cable (not shown)comprises twelve subscriber optical fibers. The FDT 160 of FIGS. 9A-9Calso includes an output opening 174 defined in the sidewall 168. Theoutput opening 174 comprises a plurality of fiber optic outputreceptacles 156 adapted to receive fiber optic connectors, such as froma subscriber drop optical fiber (not shown), to optically connect thefiber optic connector to a respective one of the input optical fibers.The FDTs of further embodiments of the present invention are adapted toreceive any number of input optical fibers and to provide any number offiber optic output receptacles.

Similar to the direct cable input FDT 140 of FIGS. 8A-8D, themulti-fiber connector input FDT 160 of FIGS. 9A-9C provides asignificant advantage over prior art FDTs in that the FDT 140 provideseasy installation and connectivity, as well as requiring significantlyless volume than prior art FDTs. As mentioned above, prior art FDTstypically provide a density of receptacles per unit of volume of thehousing of about 0.042 receptacles/in³. However, the FDT 160 of FIGS.9A-9C generally defines (not including the mounting flanges or removableportion area) a width of 2.09 inches, a height of 1.35 inches, and adepth of 0.55 inches while providing 12 receptacles for subscriberoptical fibers. Therefore, the FDT 160 provides a density of receptaclesper unit of volume of the housing of about 7.73 receptacles/in³, whichis a significant improvement in density over the prior art. Variousembodiments of the present invention preferably provide multi-fiberconnector input FDTs having a density of receptacles per unit of volumeof the housing from about 1.0 receptacles/in³ to about 40receptacles/in³, more preferably a density of receptacles per unit ofvolume of the housing from about 5.0 receptacles/in³ to about 20receptacles/in³, and still more preferably a density of receptacles perunit of volume of the housing from about 6.0 receptacles/in³ to about 12receptacles/in³

Referring now to the multi-fiber connector input FDTs of FIGS. 10A-11C,each FDT 180 and 200 are similar to the multi-fiber connector input FDT160 of FIGS. 9A-9C but provide the input openings 182 and 202 atslightly different positions and provide eight MU fiber optic outputreceptacles 184 and 204 of the output openings 186 and 206 as opposed tothe twelve 5 mm fiber optic output receptacles 156 (for receiving 5 mmoptical connectors). The FDTS 182 and 202 also do not include mountingflanges and/or the removable portion; however, further embodiments ofthe present invention include FDTs that include any combination of thefeatures described herein. The FDT 180 of FIGS. 10A-10C includes theinput opening 182 in the sidewall 188 such that the input openingdefines an input axis 190 generally orthogonal to the input opening 182and the output opening 186 defines an output axis 192 generallyorthogonal to the output opening, such that the input axis and theoutput axis are generally orthogonal to one another. The input axis 190and the output axis 192 of the openings of the FDT 160 of FIGS. 9A-9Care also orthogonal to one another; however, the input opening of theFDT 180 of FIGS. 10A-10C has been recessed a significant amount toprotect the multi-fiber connector 194 of the subscriber optical cableand to further reduce the amount of area required by the FDT and itsrelated connectors. Similarly, the FDT 200 of FIGS. 11A-11C defines aninput axis 210 and an output axis 212 that are generally parallel to oneanother. Therefore, the FDTs of various embodiments of the presentinvention provide numerous option when selecting the proper FDT to beused in a particular location, with or without particular connectors,with a particular orientation, and the like.

FIGS. 12A-14D illustrate fiber optic hardware components associated withthe LCPs of various embodiments of the present invention. The fiberoptic hardware components are illustrated to scale relative to similarprior art components to illustrate the differences in sizes and/ororientations achievable using microstructured optical fiber of thepresent invention, as described more fully below. Turning now to thefiber optic splice tray assembly 220 of FIGS. 12A-12C, the fiber opticsplice tray assembly comprises a frame 224 defining a base 226 and aplurality of sidewalls 228 joined to the base, wherein a volume of thesplice tray assembly is defined by a length of the base, a width of thebase, and a height of the sidewalls. The splice tray assembly alsoincludes a splice tray 230 comprising a plurality of splice holders 232joined to the splice tray. The splice holders 232 are adapted toselectively receive a plurality of splices 234 of optical fibers 236.The splice holders 234 are generally angled relative to the sidewalls228 of the frame 224. At least a portion of the sidewalls 228 definesslack storage generally around the splice tray 230, wherein the slackstorage provides for a sufficient amount of slack of the optical fibers236 associated with the splice generally sufficient for a technician tooptically connect the optical fibers with the splice 234. As shown bestin FIG. 10B, the splice tray assembly 220 provides slack storage alongonly two sidewalls 228 of the frame 224.

Based in part upon the use of the microstructured optical fiberdescribed below, the splice tray assembly 220 is adapted to provide asignificant improvement in the density of splices per unit of volume ofthe splice tray assembly, thus reducing the size, number, and/or costsof splice tray assemblies required for a particular application. Whereasprior art splice tray assemblies 236 generally define along the exteriora width of 3.94 inches, a length of 9.34 inches, and a depth of 0.4inches while providing 24 splice holders, the splice tray assembly ofthe illustrated embodiment of the present invention generally definesalong the exterior a width of 2.44 inches, a length of 6.34 inches, anda depth of 0.4 inches while providing 24 splice holders. Therefore, theprior art splice tray assemblies define a density of splice holders perunit of volume of the splice tray assembly of about 1.63 singlesplices/in³ and about 3.26 mass fusion splices/in³, and the splice trayassembly of the illustrated embodiment defines a density of spliceholders per unit of volume of the splice tray assembly of about 3.87single splices/in³ and about 7.76 mass fusion splices/in³. Variousembodiments of the present invention preferably provide a density ofsplice holders per unit of volume of the splice tray assembly of atleast 3 single splices/in³ or at least 6 mass fusion splices/in³, morepreferably a density of splice holders per unit of volume of the splicetray assembly of at least 5 single splices/in³ or at least 10 massfusion splices/in³, and still more preferably a density of spliceholders per unit of volume of the splice tray assembly of at least 8single splices/in³ or at least 16 mass fusion splices/in³.

Turning now to the fiber optic splitter module 240 of FIGS. 13A-13C, thesplitter module optically connects at least one input optical fiber 242and a plurality of output optical fibers 244. The splitter modulecomprises a housing 246 having at least one opening 248 therethrough,wherein the opening defines an opening axis 250 generally orthogonal tothe opening. The splitter module also includes a splitter 252 within thehousing 246, wherein the input optical fiber 242 is optically connectedto the plurality of output optical fibers 244 by the splitter 252. Thesplitter 252 defines a splitter axis 254 generally aligned with theinput optical fiber 242 and the plurality of output optical fibers 244proximate the splitter. In the splitter module 240 of FIGS. 13A-13C, thesplitter axis 254 is generally orthogonal to the opening axis 250. Itshould be noted that the splitter module 240 does not include a slackloop for either the input optical fiber 242 or the output optical fiber244, based in part upon the performance of the microstructured opticalfiber used in some embodiments of the present invention.

Also based in part upon the use of the microstructured optical fiberdescribed below, the splitter module 240 is adapted to provide asignificant improvement in the density of output optical fiber splitsper unit of volume of the splitter module housing, thus reducing thesize, number, and/or costs of splitter modules required for a particularapplication. Whereas prior art splitter module 256 generally definesalong the exterior a width of 3.07 inches, a length of 4.85 inches, anda depth of 0.92 inches while providing 32 output fiber splits, thesplice tray assembly of the illustrated embodiment of the presentinvention generally defines along the exterior a width of 3.47 inches, alength of 1.83 inches, and a depth of 0.83 inches while providing 32output fiber splits. Therefore, the prior art splice tray assembliesdefine a density of output optical fiber splits per unit of volume ofthe splitter module housing of about 2.34 splits/in³, and the splicetray assembly of the illustrated embodiment density of output opticalfiber splits per unit of volume of the splitter module housing of about6.07 splits/in³. Various embodiments of the present invention preferablyprovide a density of output optical fiber splits per unit of volume ofthe splitter module housing of about 4 splits/in³ to about 10splits/in³, more preferably a density of output optical fiber splits perunit of volume of the splitter module housing of about 5 splits/in³ toabout 8 splits/in³, and still more preferably a density of outputoptical fiber splits per unit of volume of the splitter module housingof about 6 splits/in³ to about 7 splits/in³. It should be appreciatedthat the numbers given above are for 1×32 splitters and that additionalsplitter modules of the present invention generally define the samevolume while including alternative numbers of splits, such that theamounts given above should be adjusted accordingly based upon thesplitter ratio of the actual splitter(s) used in the splitter module.

Turning now to the fiber optic routing guide 260 of FIGS. 14A-14E, thefiber optic routing guide is adapted for use in an enclosure of a fiberoptic network, such as the housing (and/or splitter end of the cableassembly) of an LCP as described above, to provide one non-limitingexample. The routing guide 260 is adapted to store slack of an opticalfiber 262, such as an optical fiber having an outer diameter of 900 μmto provide one non-limiting example. The routing guide 260 comprises ahousing 264 defining an outer surface 266 generally located between atop surface 268 and a bottom surface 270. The routing guide 260 alsoincludes a core portion 272 defining a fiber routing surface 274 alongthe perimeter of the core portion between the top surface 268 and thebottom surface 270. The core portion 272 is generally centered in thehousing 264, and the fiber routing surface is adapted to receive therouted optical fiber 262. The routing guide 260 further includes anouter wall 276 joined to the core portion 272. The outer wall 276defines the outer surface 266 of the housing 264 and defines an innersurface 278 opposite the outer surface and facing the fiber routingsurface 274 of the core portion 272. For the routing guide 260 of FIGS.14A-14C, the fiber routing surface 278 generally defines a plurality ofcurved surfaces having a common center, the outer surface 266 generallydefines a plurality of curved surfaces having a common center, and thecenters for both the fiber routing surface and the outer surfacecorrespond (same center). Tab portions 280 extending radially from thefiber routing surface 274 and the inner surface 278. The volume of therouting guide 260 is defined along the outer surface 266 between the topsurface 268 and the bottom surface 270.

Based in part upon the use of the microstructured optical fiberdescribed below, the routing guide 260 of FIGS. 14A-14C is adapted toprovide a significant improvement in the amount of length of opticalfiber stored by the routing guide per unit of volume of the housing,thus reducing the size, number, and/or costs of routing guides requiredfor a particular application. Whereas prior art routing guides 282generally define an outer diameter along the outer surface of 2.50inches and a height of 0.56 inches while being able to store 323 inchesof 900 μm optical fiber, the routing guide of the illustrated embodimentof the present invention generally defines an outer diameter along theouter surface of 1.05 inches and a height of 0.56 inches while beingable to store 290 inches of 900 μm optical fiber. Therefore, the priorart routing guides is adapted to store an amount of length of opticalfiber per unit of volume of the housing of about 6.12 inches of 900 μmdiameter optical fiber/in³, and the routing guide of the illustratedembodiment is adapted to store an amount of length of optical fiber perunit of volume of the housing of about 13.1 inches of 900 μm diameteroptical fiber/in³. Various embodiments of the present inventionpreferably store an amount of length of optical fiber per unit of volumeof the housing of about 10 inches of 900 μm diameter optical fiber/in³to about 20 inches of 900 μm diameter optical fiber/in³, more preferablystore an amount of length of optical fiber per unit of volume of thehousing of about 11 inches of 900 μm diameter optical fiber/in³ to about18 inches of 900 μm diameter optical fiber/in³, and still morepreferably store an amount of length of optical fiber per unit of volumeof the housing of about 13 inches of 900 μm diameter optical fiber/in³to about 15 inches of 900 μm diameter optical fiber/in³. Still furtherrouting guides of further embodiments of the present invention includedifferently shaped and/or sized routing guides adapted to holdalternative lengths of optical fibers having alternative diameters.

Various embodiments of the present invention are adapted to include bendperformance optical fibers. One example of bend performance opticalfiber is a microstructured optical fiber having a core region and acladding region surrounding the core region, the cladding regioncomprising an annular hole-containing region comprised ofnon-periodically disposed holes such that the optical fiber is capableof single mode transmission at one or more wavelengths in one or moreoperating wavelength ranges. The core region and cladding region provideimproved bend resistance, and single mode operation at wavelengthspreferably greater than or equal to 1500 nm, in some embodiments alsogreater than about 1310 nm, in other embodiments also greater than 1260nm. The optical fibers provide a mode field at a wavelength of 1310 nmpreferably greater than 8.0 microns, more preferably between about 8.0and 10.0 microns. In preferred embodiments, optical fiber disclosedherein is thus single-mode transmission optical fiber.

In some embodiments of the present invention, the microstructuredoptical fibers disclosed herein comprises a core region disposed about alongitudinal centerline and a cladding region surrounding the coreregion, the cladding region comprising an annular hole-containing regioncomprised of non-periodically disposed holes, wherein the annularhole-containing region has a maximum radial width of less than 12microns, the annular hole-containing region has a regional void areapercent of less than about 30 percent, and the non-periodically disposedholes have a mean diameter of less than 1550 nm.

By “non-periodically disposed” or “non-periodic distribution”, it ismeant that when one takes a cross-section (such as a cross-sectionperpendicular to the longitudinal axis) of the optical fiber, thenon-periodically disposed holes are randomly or non-periodicallydistributed across a portion of the fiber. Similar cross sections takenat different points along the length of the fiber will reveal differentcross-sectional hole patterns, i.e., various cross-sections will havedifferent hole patterns, wherein the distributions of holes and sizes ofholes do not match. That is, the holes are non-periodic, i.e., they arenot periodically disposed within the fiber structure. These holes arestretched (elongated) along the length (i.e. in a direction generallyparallel to the longitudinal axis) of the optical fiber, but do notextend the entire length of the entire fiber for typical lengths oftransmission fiber.

For a variety of applications, it is desirable for the holes to beformed such that greater than about 95% of and preferably all of theholes exhibit a mean hole size in the cladding for the optical fiberwhich is less than 1550 nm, more preferably less than 775 nm, mostpreferably less than 390 nm. Likewise, it is preferable that the maximumdiameter of the holes in the fiber be less than 7000 nm, more preferablyless than 2000 nm, and even more preferably less than 1550 mm, and mostpreferably less than 775 nm. In some embodiments, the fibers disclosedherein have fewer than 5000 holes, in some embodiments also fewer than1000 holes, and in other embodiments the total number of holes is fewerthan 500 holes in a given optical fiber perpendicular cross-section. Ofcourse, the most preferred fibers will exhibit combinations of thesecharacteristics. Thus, for example, one particularly preferredembodiment of optical fiber would exhibit fewer than 200 holes in theoptical fiber, the holes having a maximum diameter less than 1550 nm anda mean diameter less than 775 nm, although useful and bend resistantoptical fibers can be achieved using larger and greater numbers ofholes. The hole number, mean diameter, max diameter, and total void areapercent of holes can all be calculated with the help of a scanningelectron microscope at a magnification of about 800× and image analysissoftware, such as ImagePro, which is available from Media Cybernetics,Inc. of Silver Spring, Md., USA.

The optical fibers disclosed herein may or may not include germania orfluorine to also adjust the refractive index of the core and or claddingof the optical fiber, but these dopants can also be avoided in theintermediate annular region and instead, the holes (in combination withany gas or gases that may be disposed within the holes) can be used toadjust the manner in which light is guided down the core of the fiber.The hole-containing region may consist of undoped (pure) silica, therebycompletely avoiding the use of any dopants in the hole-containingregion, to achieve a decreased refractive index, or the hole-containingregion may comprise doped silica, e.g. fluorine-doped silica having aplurality of holes.

In one set of embodiments, the core region includes doped silica toprovide a positive refractive index relative to pure silica, e.g.germania doped silica. The core region is preferably hole-free. In someembodiments, the core region comprises a single core segment having apositive maximum refractive index relative to pure silica Δ₁ in %, andthe single core segment extends from the centerline to a radius R1. Inone set of embodiments, 0.30%<Δ₁<0.40%, and 3.0 μm<R1<5.0 μm. In someembodiments, the single core segment has a refractive index profile withan alpha shape, where alpha is 6 or more, and in some embodiments alphais 8 or more. In some embodiments, the inner annular hole-free regionextends from the core region to a radius R2, wherein the inner annularhole-free region has a radial width W12, equal to R2−R1, and W12 isgreater than 1 μm. Radius R2 is preferably greater than 5 μm, morepreferably greater than 6 μm. The intermediate annular hole-containingregion extends radially outward from R2 to radius R3 and has a radialwidth W23, equal to R3−R2. The outer annular region 186 extends radiallyoutward from R3 to radius R4. Radius R4 is the outermost radius of thesilica portion of the optical fiber. One or more coatings may be appliedto the external surface of the silica portion of the optical fiber,starting at R4, the outermost diameter or outermost periphery of theglass part of the fiber. The core region and the cladding region arepreferably comprised of silica. The core region is preferably silicadoped with one or more dopants. Preferably, the core region ishole-free. The hole-containing region has an inner radius R2 which isnot more than 20 μm. In some embodiments, R2 is not less than 10 μm andnot greater than 20 μm. In other embodiments, R2 is not less than 10 μmand not greater than 18 μm. In other embodiments, R2 is not less than 10μm and not greater than 14 μm. Again, while not being limited to anyparticular width, the hole-containing region has a radial width W23which is not less than 0.5 μm. In some embodiments, W23 is not less than0.5 μm and not greater than 20 μm. In other embodiments, W23 is not lessthan 2 μm and not greater than 12 μm. In other embodiments, W23 is notless than 2 μm and not greater than 10 μm.

Such fiber can be made to exhibit a fiber cutoff of less than 1400 nm,more preferably less than 1310 nm, a 20 mm macrobend induced loss at1550 nm of less than 1 dB/turn, preferably less than 0.5 dB/turn, evenmore preferably less than 0.1 dB/turn, still more preferably less than0.05 dB/turn, yet more preferably less than 0.03 dB/turn, and even stillmore preferably less than 0.02 dB/turn, a 12 mm macrobend induced lossat 1550 nm of less than 5 dB/turn, preferably less than 1 dB/turn, morepreferably less than 0.5 dB/turn, even more preferably less than 0.2dB/turn, still more preferably less than 0.01 dB/turn, still even morepreferably less than 0.05 dB/turn, and a 8 mm macrobend induced loss at1550 nm of less than 5 dB/turn, preferably less than 1 dB/turn, morepreferably less than 0.5 dB/turn, and even more preferably less than 0.2dB-turn, and still even more preferably less than 0.1 dB/turn.

The fiber of some embodiments of the present invention comprises a coreregion that is surrounded by a cladding region that comprises randomlydisposed voids which are contained within an annular region spaced fromthe core and positioned to be effective to guide light along the coreregion. Other optical fibers and microstructured fibers may be used inthe present invention. Additional features of the microstructuredoptical fibers of additional embodiments of the present invention aredescribed more fully in pending U.S. patent application Ser. No.11/583,098 filed Oct. 18, 2006, and provisional U.S. patent applicationSer. Nos. 60/817,863 filed Jun. 30, 2006; 60/817,721 filed Jun. 30,2006; 60/841,458 filed Aug. 31, 2006; and 60/841,490 filed Aug. 31,2006; all of which are assigned to Corning Incorporated and thedisclosures of which are incorporated by reference herein.

Many modifications and other embodiments of the invention set forthherein will come to mind to one skilled in the art to which theinvention pertains having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the invention is not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims. It isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

1-43. (canceled)
 44. A fiber optic splitter module for opticallyconnecting at least one input optical fiber and a plurality of outputoptical fibers, the splitter module comprising: a housing having atleast one opening therethrough, wherein the opening defines an openingaxis generally orthogonal to the opening; and a splitter within thehousing, wherein the input optical fiber is optically connected to theplurality of output optical fibers by the splitter, wherein the splitterdefines a splitter axis generally aligned with the input optical fiberand the plurality of output optical fibers; wherein the splitter axis isgenerally orthogonal to the opening axis.
 45. A splitter moduleaccording to claim 44, wherein the input optical fiber and the pluralityof output optical fibers are routed within the housing generally withouta slack loop.
 46. A splitter module according to claim 44, wherein thesplitter module defines a density of output optical fiber splits perunit of volume of the housing of at least 5 splits/in³.
 47. A splittermodule according to claim 44, wherein the splitter module defines adensity of output optical fiber splits per unit of volume of the housingfrom about 4 splits/in³ to about 10 splits/in³.
 48. A splitter moduleaccording to claim 44, wherein at least one of optical fiber of theplurality of output optical fibers comprises a microstructured opticalfiber comprising a core region and a cladding region surrounding thecore region, the cladding region comprising an annular hole-containingregion comprised of non-periodically disposed holes.
 49. A splittermodule according to claim 48, wherein the microstructured fiber has an 8mm macrobend induced loss at 1550 nm of less than 0.2 dB/turn.